[Dead Parrot]

If yours is similar to mine, then you need one wire from the cab tank selector switch to the solenoid valve. Power on selects one side, power off selects the other. IIRC a pink wire.

Each sending unit will connect to a wire from the switch as well, IIRC a brown wire, should be two, one for each tank. A second short ground wire connects to the frame from each sending unit. You will need to match the sending wire to the valve position so you are reading the level in the side being used.

A short hose will go from the source pipe of each sending unit to the input of the valve. A 3rd short hose will go from the output of the valve to the metal frame pipe that runs up to the pump.

No regulator on the suction side of the system.

Use a short hose from each sending unit vent pipe for the vent system. Originally, the vent hose terminated in a plastic thing with a loose cap. Not sure that is made anymore. Some folks have used a rear end vent as a substitute.

Check wire colors from one of the wiring diagrams available on this site before proceeding. Verify with a volt/ohm meter as well. Who knows what a PO may have substituted at one point. And my memory of colors could be wrong.